The invention relates to a method for producing a piston with a cooled ring carrier, consisting of a ring carrier part and a sheet-metal part linked with it.
Such a ring carrier and a corresponding production method are known from DE 19750021. The cooled ring carrier is Alfin-bonded in an aluminum-base melt before having the piston material cast around it. During Alfin bonding, a layer of iron aluminides forms on the iron base material, which layer serves as a bonding layer between the aluminum material and the iron material of the ring carrier in the piston. The ring carrier part normally consists of a Niresist material with a lamellar graphite structure.
It has now been shown that during Alfin bonding of the cooled ring carrier, the gas pressure in the cooling channel increases and, since the ring carrier material is not always present in pore-free form, that in an individual case, surprisingly, entrapped air can actually escape from the cooling channel. This results in the formation of oxide skins in the Alfin bath, which skins adhere to the cooled ring carrier and represent defects in the ring carrier bond on the finished piston.